The present invention relates generally to microsurgical and ophthalmic systems and more particularly to an ophthalmic system employing a vacuum-operated aspiration system with a removable fluid collection cassette having reusable and disposable components and adapted for use with an optically sensed fluid level shutoff system.
In aspirating fluids and tissue from the surgical situs, as during eye surgery, it is the present practice to draw the aspiration fluid into a disposable cassette by connecting the aspirating instrument to the cassette and then introducing a vacuum into the cassette using a pump or the like. To gain more precise control over the aspiration suction, the flexible tubing between the aspirating instrument and the cassette is conventionally routed through a pinch valve arrangement which squeezes the tubing in response to a remote control mechanism (typically a foot pedal) operated by the surgeon.
In order to ensure that the aspirating vacuum changes quickly in response to the surgeon's control, some conventional cassettes employ a reduced volume primary collection canister with means for periodically emptying the primary canister into a larger secondary canister. Relatively complex tubular systems, valves and often several vacuum sources are required to implement such systems. Aside from adding to the complexity of the ophthalmic system, the additional tubing, valves and pumps represents considerable additional expense. This is particularly true in the case of present day ophthalmic cassettes which are designed to be discarded after a single use.
The ophthalmic cassette of the present invention offers much improvement over the present day state of the art. The inventive cassette greatly simplifies the interconnecting tubing and valving arrangements needed for precise control of the aspiration suction. This is accomplished while, at the same time, providing a cassette with reusable components, thereby saving some of the surgical equipment costs.
Accordingly, the invention provides a microsurgical cassette for use in a vacuum-operated microsurgical system having an aspirating instrument. The cassette comprises a plurality of interconnected vessel walls forming a fluid containment vessel having an interior. One of the vessel walls defines a recess which has a first wall portion in common with the vessel interior. An aspiration port is disposed in the first wall portion so that it communicates between the recess and the vessel interior. A vacuum port is disposed on one of the vessel walls and communicates with the vessel interior, for introducing a vacuum into the interior by connection to a vacuum pump, for example. The fluid containment vessel comprises an autoclavable plastic material capable of being sterilized and reused.
The invention further comprises a reusable coupler member of a size and shape for removable frictional fit within the recess. The coupler member has a first nipple for insertion and communication with the aspiration port. The coupler has a second nipple for communicating with an external aspirating instrument of the microsurgical system. The coupler has an internal passageway which extends and communicates between the first and second nipples and at least a portion of the coupler through which the passageway extends is made of a resilient and deformable plastic material. Deformation of the coupler portion is capable of closing the passageway and thereby controlling aspiration of fluid and tissue from the surgical situs.
The second nipple includes an elongated end portion and an intermediate portion which has a structurally weakened breakaway section for severing the elongated end portion from the remainder of the second nipple. The second nipple is insertable through an opening in the recess, which opening communicates with the exterior of the cassette for connection to the external aspirating instrument through a flexible tubing, for example. During the installation of the reusable coupler, this elongated end is inserted through the recess opening and is manually pulled through the opening to assist in seating the coupler in the recess. Further pulling on the elongated end portion causes it to break away from the remainder of the second nipple, leaving the second nipple properly positioned within the opening through the recess. Once the elongated end portion has been broken away in this fashion, the assembled cassette is ready to use.
The coupler member has a generally I-shaped body portion with enlarged end portions for frictional fit within the recess, leaving the middle portion free for grasping with the fingertips when removing the coupler from the recess. The coupler member is also formed to provide a reflux chamber, and a tube may also be connected to the coupler member to carry the aspirant to the bottom of the cassette.